1. Field of the Invention
The invention relates to a micro array chip having wells using for reaction vessels where in vivo samples are subjected to enzyme treatment, formation of derivatives, PCR (polymerase chain reaction), Sanger""s reaction, etc, and more relates to the micro array chip for reaction vessels of small capacity.
2. Description of the Related Art
When Polymerase chain reaction (hereinafter, referred to PCR) and other reactions are performed with small amounts of sample, microtiter plates having 96 or 384 wells are conventionally used as reaction vessels.
In order to perform reaction with microtiter plates, the required sample quantity is from 20 to 40 xcexcL for a 96-well plate and from 5 to 10 xcexcL for a 384-well plate.
With recent improvements in the performance of DNA sequencer and other equipment, it has become possible to analyze small amounts of sample. As a result, pretreatments such as PCR and Sanger""s reaction can now be performed on small sample quantities.
A cost of reagents has been a great burden when reactions are performed on the quantity using a conventional microtiter plate. Therefore, it is preferred to process samples in smaller quantities.
The microtiter plate is an array of interconnected single wells and its bottom follows a shape of wells.
In the case of reactions such as PCR that require heat treatment, temperature control is performed with a heat block being in contact with a bottom of the microtiter plate.
Since the bottom of the microtiter plate is uneven, and further a capacity of each well is fairly large, the heat block is fabricated in order to conform to the shape of the bottom of the microtiter plate. Therefore, when using microtiter plates of different well numbers it is inconvenient to change the heat blocks in accordance with the microtiter plates.
It is an object of the invention to provide a micro array chip that can be changed for another chip of a different well number or shape without changing a heat block. Therefore, the micro array chip can be handled conveniently and at lower cost.
In a first aspect of the invention, a micro array chip comprising:
a chip body having a plurality of openings on a top surface of the chip body and a bottom surface with a flat shape; and
a plurality of recesses formed in the openings, each of the recesses having with capacity of a few microliters or less,
wherein a distance between a bottom of the recesses and the bottom surface is 300 micrometers or less.
In the second aspect of the invention, the chip body has a first member having a flat-plate shape with a plurality of through-holes, and a thin film has a thickness of 300 micrometers or less, and the recesses are formed by closing the through-holes with the thin film.
According to the first and second aspects of the invention, an invention can be attained by a micro array chip with a plurality of recesses that are open to a surface of a chip body in flat plate form and which have a capacity of less than a few microliters and a bottom with a wall thickness of 300 micrometers or less.
The recesses in the chip body have a very small capacity, so if they are used as reaction vessels, samples can be processed in smaller quantities. In addition, a plurality of reaction vessels can be stacked one on another.
Since the bottom of each recess has a wall thickness of 300 micrometers or less, the efficiency of heat conduction from a heat block to the bottom of the chip body is high. Accordingly, a temperature of a liquid in the recesses can be effectively controlled as long as the heat block contacts the bottom of each recess.
The microtiter plates require heat blocks that conform to the shapes of wells in different plates. In the present invention, it is not necessary to use a planar heat block of different types of micro array chip.
The recesses may be formed in the chip body. Alternatively, due to a small capacity of the recesses, through-holes may be formed in the chip body, and then the openings at the bottom may be closed with a thin film so that the recesses are formed. It has an advantage of facilitating chip production.
In the third aspect of the invention, some recesses are used as reaction vessels and others are used for lowering a heat capacity of the whole micro array chip.
According to the third aspect of the invention, through-holes or recesses may be formed in those areas of the chip body where no recesses are formed to provide reaction spaces. This contributes to lowering a heat capacity of the micro array chip taken as a whole and to enhancing an efficiency of temperature control in each reaction space.
In the forth aspect of the invention, inner surface of the recesses are treated against adherence of in vivo samples.
According to the forth aspect of the invention, since very small amounts of samples are processed, inner surfaces of the recesses are preferably treated against adherence of in vivo samples. This contributes to enhancing the reaction efficiency.
In the fifth aspect of the present invention, a sealing member covers the openings to form closed space in each of the recesses.
According to the fifth aspect of the invention, in the case of performing reaction using a very small amount of sample in reaction vessels, the recesses in the micro array chip are preferably sealed. Accordingly, the reagent concentrations will not vary due to evaporation and the reaction will not stop on account of insufficient mixing. To this end, the micro array chip preferably has a sealing member fitted on the open tops of the recesses to provide a closed space in each of them.
After reaction reagents are injected into the recesses in the chip, the sealing member is applied to the open top of the chip so that the reaction reagents are confined in each of the recesses.
In the six aspect of the invention, the chip body has a protrusion portion around each of the openings, the protrusion portion comes into contact with the sealing member to securely seal the recesses.
Raising the perimeter of the open top of each recess from the surface of the chip body is advantageous for the purpose of ensuring a higher level of airtightness in the openings after they are closed with the sealing member.
It is difficult to heat a liquid in the wells through heat conduction from lateral sides of the chip, so it is preferred to control a temperatures of both the upper and lower surfaces of the chip by the Pettier effect and thereby allow temperature control on the upper surface of the chip.